Typing in portrait mode on the N900 is going to be a pain no matter how. In practice players willing to type (chat) are going to stay in landscape.

Chatting is less frequent in blitz / lightning chess for obvious reasons. There is where you need more real estate in the board to have less risk os mistakes in moves. Also you want to save as many unnecessary processes as possible to save CPU and bandwidth, improving the responsiveness of the system when every tenth of a second count.

So yes, I believe it makes sense to have specialized functions for portrait and landscape. I'm not sure at all about changing orintation during a game, but at least the difference should be clear before starting.

I wil keep promoting the project in order to find more developers. Most of the developers I know come from the GNOME side, though...